From mboxrd@z Thu Jan 1 00:00:00 1970 From: jiangyiwen Subject: Re: [V9fs-developer] [PATCH] net/9p: fix potential refcnt problem of trans module Date: Wed, 28 Mar 2018 11:38:40 +0800 Message-ID: <5ABB0E40.9000002@huawei.com> References: <1522154942-57339-1-git-send-email-cgxu519@gmx.com> <5ABAF980.5060406@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset="gbk" Content-Transfer-Encoding: 8bit Cc: , , , , , To: "cgxu519@gmx.com" Return-path: Received: from szxga05-in.huawei.com ([45.249.212.191]:6707 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751150AbeC1Diy (ORCPT ); Tue, 27 Mar 2018 23:38:54 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On 2018/3/28 10:52, cgxu519@gmx.com wrote: > 在 2018年3月28日，上午10:10，jiangyiwen 写道： >> >> On 2018/3/27 20:49, Chengguang Xu wrote: >>> When specifying trans_mod multiple times in a mount, >>> it may cause inaccurate refcount of trans module. Also, >>> in the error case of option parsing, we should put the >>> trans module if we have already got. >>> >>> Signed-off-by: Chengguang Xu >>> --- >>> net/9p/client.c | 5 ++++- >>> 1 file changed, 4 insertions(+), 1 deletion(-) >>> >>> diff --git a/net/9p/client.c b/net/9p/client.c >>> index b433aff..7ccfb4b 100644 >>> --- a/net/9p/client.c >>> +++ b/net/9p/client.c >>> @@ -190,7 +190,9 @@ static int parse_opts(char *opts, struct p9_client *clnt) >>> p9_debug(P9_DEBUG_ERROR, >>> "problem allocating copy of trans arg\n"); >>> goto free_and_return; >>> - } >>> + } >>> + >>> + v9fs_put_trans(clnt->trans_mod); >> >> I think this should return error if using multiple times >> in a mount. > > Fail or retake are just different policies how to deal with this kind of situation, > most filesystems in kernel choose retaking new value, so we’d better keep consistence > with others unless there is a necessary reason. > > Thanks, > Chengguang. > Yes, you're right, most filesystems retake indeed the new value. Reviewed-by: Yiwen Jiang > >> >>> clnt->trans_mod = v9fs_get_trans_by_name(s); >>> if (clnt->trans_mod == NULL) { >>> pr_info("Could not find request transport: %s\n", >>> @@ -226,6 +228,7 @@ static int parse_opts(char *opts, struct p9_client *clnt) >>> } >>> >>> free_and_return: >>> + v9fs_put_trans(clnt->trans_mod); >> >> This looks good. >> >>> kfree(tmp_options); >>> return ret; >>> } >>> >> >> > > > . >